Process for the elimination of hydrogen sulphide in fuel gas



' F. sPERR. JR

PnocEss Fon THE ELIuINA'rI'ioN or HYDROGEN sULPHIDE In FUEL @As .lu'l'yA 21s, 1931.

2 Smets-snee: 1

Filed Dec. 12, 1921 July 2,8, 1931. F. wysPERR, JR Y 18l55933 IPROCESS'FOR THE ELIIINATION OF vI'IYDROGEN SULPHIDE INFUEL GAS Filed Deo. 12, 192; 2 sheets-snaai 2 Slim Pafefe July. 28,- 11931511 ,g l

OFFICE j FREDERCK W. srnnnyaa., on PITTSBURGH," PENNSYLVANIA, AssIeNon` To `'rrrn y sY-LVANIA ".TKOIPPERS COMFANYQOF PITTSBURGH, PENNSYLVANIA, A `'C0RIPORMLTION 0F PENN? di c A5.jrRocEss :non 'remv ELIMrNarr10Ny or H'YnRoGEN SULPHIDE IN FUEL @As s I f appneatiqnnied :beamten 1a, 1921.1 serial No., 521,913.

VThis invention relates generally to 'elimination vof `hydrogen sulphide in fuel lgasy suchy las",co'a1 gas andthe like, so asto effect the eX;`

tinction'of` that noxious constituent of 'such r 3y gas;y and ndov so4 by acontinuous', regenerative,rv

f ance vvithvthe process4l described and claimed y intlylewprior LettersfPatentcf the United States ofDavid L. Jacobson, f dated Septem` ber 6,192.1, No. V1,890,()3755.Broadly stated k'such gas' 'purification process consists 'in bringingfthe gas tobe purified intoy direct conlu'i'd 'Wash{InethodV practically and economi# e cally: operable in the vlarge vscale commercial treatment vofi such gas; f and the invention 1s aniniportant"development'of thegasl purificar tion" process operating generally in 'accordV-r tact Withanjalkaline absorbent'vagent'such as a solution of sodium carbonate, to absorb the n'xiul'constituents .from the' gas, and then subjecting the absorbent agent kcontainingthe absorbed' impurities to aeration.V to remove the absorbed impurities and `t0 veffect a" r@-` generation of theabsorbent agent, with the resi-llt that the v`absorbent agentzisavailable 'forfurther gas purification."v Inthat stage of' the gas purification process' in Whichthe regeneration' of the fouled absorbent agent" 1s effected, the 'air nremoves the hydrogensulr` yphidefrorn`- the absorbent agent, andfcarries the hydrogensulphide out of the actiier eml Y ployedfor the regeneration stage of the proc- 40. above, the inventionr has for further obj ect-sr such; other" improvements or advantages in operationandfresult's*as arey found to yobtain devicesV herein-4 attendescri'bedorclaimed.YK

ess."A 'By thelpresent invention, the hydrogenly sulphide is removedy and recovered from' the I air discharged from theactier, Withthe ree i 4sult that such dischargedfair: doesY not become v a sourcel of nuisance in 'thevicinityzof the gas -purication plant. As an incidental byQ-prod-r` uct, some free'sulphuris recovered-.Qy Y y In addition to the generaly objects recited intheprocess, structures and lin-the accompanying? drawings forming a part oi thisy speci'cati'on "and showing, forl purposes of exemplificatioma.preferred*form and Vmanner in; which the'invention maybe embodied and practiced, but Without limiting the claimed invention to such illustrative inn stance :V

jFig'.I l shows a partly diagrammatic repre-y j sentation of apparatus for carrying out thev v4improved process of the invention, in con-v junction with agaspurlication process such as lthat de scribed in the before mentioned paty.ent to'DavidL. Jacobson. Figr2 is an ele?" vational View of the same apparatus shovvn more d1agi-ammatically1nFig.l. v f* rln its present embodiment, theinvention is i applied to the removal of hydrogen sulphide usent` the invention.` Features of v'the 'invenvinonfalre, however, capable of other ,valuableY v applications," consequently, the inventionis f not limited in its scope to the specific use and embodimentherein'described as an illustra-Y".

tive'kexample.

According to the Jacobson gas purificationl process, there is employed a Water solution ofv` an'alkalinecompound,such as sodium carbonate, for effecting the absorption of the hydro- I f 'gen sulphide and other impurities :from the gasl The gas to be purified enters the'bottom oflthe absorber l at 3 and passing upwardly through' said `absorber is brought'into contact'with the sodium carbonate solution which is supplied to the top of the absorber from thev tioncontaining the absorbedV impurities dis;

fresh solution line 2. The purifiedv gas passes" out of they top of the absorber, and the soluf" 85 charges'from the bottomy of the absorber into a sump ll. From the sump 4, the fouled solu-' tion"isfpumped through a line 5 anddis-r charged into the ytop of the actifier 6. In the in rent ofair supplied/by the blower7 at the f bottom, and the air removes thesulphur and actifier 6, the solution meets an'upvvard cnr# othery impurities from the solution thereby-jv revivifying or regenerating the solution 'for' furthergas purification. The regenerated solution discharges into a Well or sump 8 atthev bottom of thelvactifier, fromvvhich the rej uve- 1 nated solutionl may bev pumped back thro'gh y the lineQ tothe absorber. s

The 'air containinghydrogen sulphide passes out ofthe topof the actilier through Vthe line/9. Besides hydrogen sulphide, the

.air may contain carbon dioXide and hydro-- Y gen cyanide. According to the'invention, the Y air ladeirwitli hydrogen sulphide and-other noxious constituents is brought into intimate;

contactwith a washing mixture, consisting of a suspension o f iron oxide in analiza-line sollutio-ni. Various iron compounds-z may be used'for the purpose,-.as stated later, but:retA erence is' made to iron oxide only in the pres-Y ent exemplification.W The process is carried out in a t'owerrlled withI suitablepacking'or any other suitable typ-e of washer.y VThe miX- ture of iron oxide and dissolved alkali absorbs; the hydrogen sulphide from.v the pair,

while simultaneously an oxidation ofthe absarhed sulphide-.'toffree sulphur takes place bymeans of the air present; the result of the whole aeti'onmay be summarizedy as-a conversionot hydrogen sulphide to' free' sulphur, the oxiden and dissolved alkali acting as intermediate agentstohasten the reaction; -V

Ifnbothzig, l. and Fig. 2 of. the drawings, it may be noted that there is a relatively large l airiblower (.7), andthat'whileihe.actitier` (6) andiairserubber (A) through which thesame, airj'curren-tpasses, are towers. of abouty equal'i size, each of. tli'osev towers isrmuch larger than the absorber 'towerk (l through which. the fuel Y 'gasbeingtreaeddlowsmnd thefactthat there. is, thus-preferably provided. aV volume of- .air

even' greater thanthe fuel gasV volume from which thev hydrogen sulphide is originally taken means that the proportion of. hydrogen.A sulphide carried l by that. air is as, slight as the hydrogen sulphide in the fuel gas, so

that: there is an enormous overp-lusf offfoxy-Y gen-.inthe air-scrubber in excesssoff the quan.- tum.l whose reaction frees the sulphur from. the vwash-liquor as the wash-liquor eliminates thehydrogensulphide from the flowing air. Such` agreat overplus of .oxygenV renders practical su eh continuousV regenerationof the l, wash-,liquorthat theremay. he effective elimination ot. the elusively slight. amountA of hydrogen vsulphide carriedby they large .ai-r currentand so there is-inimediate provision for purification ofA the great. air volume required. Y. to aerate'the` fouled, absorbent solution owing from they absorber in; which the. fuel gas.- is purified... Y

.its shownA inthe dra-.winzigeV the suspension; loliiron oxide. inthe alkalinesolutionis stored;

in. af circulatingl tank Bf. Here an; air 'agitatorv or other meansof agitation is provided. The. reactions may take. place partly in. this` tank.. The suspension is pumped through the line C intoy the. top of. the. tower A- where it.,meets thevv air laden with hydrogen sulphide; such mixture. of, air and hydrogen l sulphide being conveyed tothe bottomof the tower A. through theline ,9j For. practical.

purposes, it is not necessary that the whole content: of the.hydrogen` sulphide.. be removed igsiage .from the air,rit ,beingl unobjectionable to j leave small traces of hydrogen Ysulphide in the air in most cases.

However, where it is so desired, even the last traces 'of hydrogen sulphide.l can be removed byusing. theproper coneentration ol?.l alkali and proper amount of iron oXidein suspension, combinedv with proper regulationV of the rate of .flow of the air.,` The: concentration. olfdissolved.; alkali;v A

and .off suspended iron: hydroxide. may.V .be

varied las desired; in practice a 2 to 3percent suspension of iron oxide in 'a l/2. to lvpercent VSollution"*o*` sodium carbonate will; be found satisfactory. The exit Yair leaves the washer or 'towerthrough the line D vtreed of most or all; of itsv hydrogen sulphide and Jother noxiousconstitutenta'.andit is noflonger thepos.- sible source of nuisance. it might be. before.

this treatment. Atthe same time, free sul@ phun is recovered, asf loyfprodpuct.,of some.r valuej. The whole processmay be, made con.- ti'n-uous: as shown inthe attached diagrainiozt V the apparatus.V lnthe (continuous process,4

the solution containing the. suspension isdis cli a-rged; from the tower. into thev tank B tor further Vdeli-very through. the line C tor the. tower.y

.The chemicalV reactionsmay beexemplied by; ther'following equations dieiircarbona-te forming sodium sulphide y Nazeo'sleiiiseuaiis meneer Y Carbon dioxide and `hydrogen; cyanide; .presentare-alsoabsorbed.: Y

Y errzs-i-aof'sefeiigo. In addition to these reactions7 partV of ther sodium hydrogen sulphide may react with 2 he airv and free sulphur present resulting in:

the-formationof sodiumthiosulphate.. Thisn Y salt may be allowed to vaccumulate andcanbe recovered by a suitableprocess such asthat described? in. the co-pend-ing` application.. for.

Letters jPatentolt' the United Stateslof Ralph.

E.V Hall and fDavidL. Jacobson, filed` April'.V V13,1921,serial-ivo.462,136; y

` i ''Ihe freesulphur allovvedtoiaccumulate inthe suspension. f From' time to time part of the sludges may be withdrawn for the recovery of sulphur and iron oxide and fresh iron oxide and dissolved alkali'are added to mainf tain the concentration. r Instead ,ofy iron oxide, iron sulphidemaybe added tothe cir-` culating tank, Where-the air Will convert it to c iron oxide.

Suchconversion within the circulation system introduces the iron oxide 1n a fresh or nascent'st-ateinvvhich it is peculiarly active and eiicective inf its reactionvvith L hydrogen sulphide. v`'Ihe ,aerationaccomyplished'loy the air vagitator Within the circulating tank B is particularly effectlvefin promoting reactions vthere' and also in causing 'lotationof the treed sulphurgto facilitate skimmingit from the liquor in thetank.

n The vrprocess is carried out as mentioned above byk means of a suspension' of ironvoxldeV in an'y alkaline solution.; This fvvashing mixf ture may be obtainedfby means of a numberV u vof materials Which have essentially the same l Veffect in carrying out the reactionsl described. c

Instead of iron oxide, ferrie carbonate or f Vbasic-ferrie carbonate`V may be employed; for,

. they iron may be inthefformzof lferric hy- ;droxide ory ferrie oxide. .n kFerrous compounds n may also be employedinstead orV .the iron fo'xide, either in the ormof ferrous oxide,

ferrous carbonate` or'r ferrous hydroxide; the

ferrous compounds will have an action simiylar to the ferrie oxide, and'at the Sametime f the aeratingfprocess 'Will gradually transform them to the ferrie state. The dissolved alkali may be any substance which gives an] alkaline reaction to thesolutiomsuch as the carbonatos of sodium and potassium, ory the hydroxides of sodiuml andpotassium; or elsey alkaline magnesium kor y calcium compounds, j such as magnesium hydroxide or magnesium' 'carbonate may beadded to the suspension,

kan isused up and n0thOSlllPhate`forms,V r S0 the process is keconomical in this respect.

which has the same effect of rendering the son lution alkaline.

In another modication of the same proc-' ess, iron oxide is used in a Water suspension, instead of an alkaline solution. fThe Whole process yis carried out as before. 'Theefy iciency of removal of hydrogen sulphide is ff somewhat lovverfbut on the other hand vno ali Enough hydrogen sulphidey is Vremoved from the-air so that it is unobj ectionably and easily disposed of, Whilel free sulphur is recovered 4las a valuable productfjA 2%. to'3f% susf satisfactory. y

clude absorption ,of thehydrogen sulphide by iron oxideforming iron sulphide, anda y simultaneous oxidation'ofl iron sulphide to Y k free sulphurl by the" air present, With regen- The' Whole reacpension of iron oxidein yWater Will be found The. chemical reactions 1neration ofthe iron oxide. l tion may be summarized Vas a conversion of the hydrogen sulphide by thea'irl'present to i free sulphur, the iron oxide acting yas an intermediate-agent to hasten the action.l For' example: f f' The invention, as hereinabove set forth may be ,variously embodied Within the scop of the'claims hereinafter made. l

)I claimz' `al. In a process for removing 'hydrogen lsulphide from coal or Water gases by treatking the gases Withan alkali carbonate solu-` l tion to absorb the hydrogen sulphide, then activating the solution containing the hydro-Vr 'f c gen sulphide by passing the foul solution counter to a flow of air, the improvement Which'consists in removing the hydrogen sulphide .from the air by passing the air opposite direction. 2. In'a process sulphide from ycoal or Water gases hyp-"treatvthrough a body of iron oxide moving inthe activating the solution containing thefhydrogenV sulphide by passing theffoul solutlonfcounter to a flow of air, the improvesulphide from the foul air by passing the airA into a vessel and passing it upwardly'counter to a flow of iron oxide passing continuously downwardly" and; discharging purified air `at ing the gases With an alkali carbonate soluwy f A tion to absorbthe hydrogen sulphide, then"l ment Which yconsists in removing yhydrogen ythe top of the column of iron oxide, whereby the air containingthe greatest amount of hydrogen sulphide comes in contact with the. partially fouledk oxide, vvkand the relatively pure air comes in contact with' thefkfreshy oxide. f

In' testimony my hand..y Y c r. c c

' FREDERICK W. jSPERR, JR.

loo

rvvhereof I have hereunto setV 'f :'1o5

c. 5.5i for removingVr hydrogen 

